That brings the number of human case in DuPage County to 12. At least one of those cases has proven fatal.

Residents are being urged to take precautionary measures:

Use mosquito repellent

Wear long sleeves and pants when outdoors during peak mosquito hours, 6-9 p.m.

Drain stagnant, standing water

"We want people to be cautious," said the DuPage County Health Department's Dave Hass. "We don't want them to curtail their outdoor activities, but we know it's present, we know that the culex mosquito is carrying it all around us."

Most DuPage County communities have already carried out preventive mosquito spraying.

Health officials say cases are up nationwide in areas affected by drought and due to increased mosquito populations that carry the virus.

Experts say, despite the increased number of cases in DuPage county, they are not recommending the affected communities take any additional actions.

Health officials say one in five people infected will show symptoms such as fever, headaches, vomiting and diarrhea. Less than 1 percent of those infected will develop serious problems but people older than 50 or those with medical conditions such as cancer, diabetes and high blood pressure are at greater risk for serious illness.

Most people who contract West Nile will never know it.

At least 60 people have been infected throughout Illinois. Two have died.